The effects of tunnel channel formation on the Green Bay Lobe, Wisconsin, USA

Tunnel channel formation during the November 1996 jökulhlaup, Skeiðarárjökull, Iceland

Annals of Glaciology ◽

10.3189/172756407782282552 ◽

2007 ◽

Vol 45 ◽

pp. 95-103 ◽

Cited By ~ 23

Author(s):

Andrew J. Russell ◽

Andrew R. Gregory ◽

Andrew R.G. Large ◽

P. Jay Fleisher ◽

Timothy D. Harris

Keyword(s):

Flow Direction ◽

Peak Discharge ◽

Channel Formation ◽

Ice Flow ◽

Flow Reconstruction ◽

Subglacial Topography ◽

Mechanical Erosion ◽

Channel Orientation ◽

Subglacial Meltwater ◽

Tunnel Channel

AbstractDespite the ubiquity of tunnel channels and valleys within formerly glaciated areas, their origin remains enigmatic. Few modern analogues exist for event-related subglacial erosion. This paper presents evidence of subglacial meltwater erosion and tunnel channel formation during the November 1996 jökulhlaup, Skeiðarárjökull, Iceland. The jökulhlaup reached a peak discharge of 45 000 to 50 000 m3 s–1, with flood outbursts emanating from multiple outlets across the entire 23 km wide glacier snout. Subsequent retreat of the southeast margin of Skeiðarárjökull has revealed a tunnel channel excavated into the surrounding moraine sediment and ascending 11.5m over a distance of 160 m from a larger trough to join the apex of an ice-contact fan formed in November 1996. The tunnel channel formed via hydro-mechanical erosion of 14 000m3 to 24 000 m3 of unconsolidated glacier substrate, evidenced by copious rip-up clasts within the ice-contact fan. Flow reconstruction provides peak discharge estimates of 680±140m3 s–1. The tunnel channel orientation, oblique to local ice flow direction and within a col, suggests that local jökulhlaup routing was controlled by (a) subglacial topography and (b) the presence of a nearby proglacial lake. We describe the first modern example of tunnel channel formation and illustrate the importance of pressurized subglacial jökulhlaup flow for tunnel channel formation.

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Sedimentologic evidence for outburst floods from the Laurentide Ice Sheet margin in Wisconsin, USA: implications for tunnel-channel formation

Quaternary International ◽

10.1016/s1040-6182(01)00090-8 ◽

2002 ◽

Vol 90 (1) ◽

pp. 23-40 ◽

Cited By ~ 67

Author(s):

Paul M. Cutler ◽

Patrick M. Colgan ◽

David M. Mickelson

Keyword(s):

Ice Sheet ◽

Laurentide Ice Sheet ◽

Channel Formation ◽

Outburst Floods ◽

Tunnel Channel

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Formation of Dislocation Channels in Neutron Irradiated Molybdenum

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100096618 ◽

1972 ◽

Vol 30 ◽

pp. 672-673

Author(s):

S. Mahajan

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Ambient Temperature ◽

Room Temperature ◽

Channel Formation ◽

Early Stages ◽

Transmission Electron ◽

Three Stages ◽

Two Stages ◽

Polycrystalline Molybdenum

The evolution of dislocation channels in irradiated metals during deformation can be envisaged to occur in three stages: (i) formation of embryonic cluster free regions, (ii) growth of these regions into microscopically observable channels and (iii) termination of their growth due to the accumulation of dislocation damage. The first two stages are particularly intriguing, and we have attempted to follow the early stages of channel formation in polycrystalline molybdenum, irradiated to 5×1019 n. cm−2 (E > 1 Mev) at the reactor ambient temperature (∼ 60°C), using transmission electron microscopy. The irradiated samples were strained, at room temperature, up to the macroscopic yield point.Figure 1 illustrates the early stages of channel formation. The observations suggest that the cluster free regions, such as A, B and C, form in isolated packets, which could subsequently link-up to evolve a channel.

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Lessons learned: Designing the forest biorefinery

TAPPI Journal ◽

10.32964/tj14.9.609 ◽

2015 ◽

Vol 14 (9) ◽

pp. 609-616 ◽

Cited By ~ 1

Author(s):

FRÉDÉRIC CLERC ◽

VIRGINIE CHAMBOST ◽

PAUL STUART

Keyword(s):

Lessons Learned ◽

Green Bay ◽

Critical Information ◽

Critical Results

The objective of this TAPPI JOURNAL (TJ) special feature is to synthesize critical information and take-away messages from the 2013 TAPPI Biorefinery Design Course in Green Bay, WI, USA, based on the presentations made, as well as discussions between participants and experts. The content of this feature was developed based on notes taken during the course; synthesis of critical information; identification of some critical results and figures included here; and identification of key messages that may be useful to TJ readers.

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